zikokuhyou wo mitara, sono densya ha zyuppungo ni hassyasuru to wakatta.

In this sentence, 見たら is best understood as when I looked or after looking, not a strong hypothetical if.

• 見る = to look
• 見た = looked
• 見たら = when/after I looked; if I look/looked

The -たら form can express a condition, but it is also very commonly used for something discovered after doing an action.

So:

• 時刻表を見たら、…分かった = When I looked at the timetable, I found out ...

This pattern is very natural when the second part is a result, discovery, or new realization.

Here, と marks the content of what was understood or found out. It works a lot like that in English.

• その電車は十分後に発車する = that train leaves in ten minutes
• …と分かった = I understood/found out that ...

So the whole part:

• その電車は十分後に発車すると分かった = I found out that the train would depart in ten minutes

This と is often called the quotative or complement particle. It is used not only for literal quotes, but also for thoughts, knowledge, reports, and realizations.

Because Japanese uses the non-past form for both:

• present/future actions
• scheduled events

発車する here means something like:

• will depart
• is scheduled to depart

The speaker looked at the timetable and learned about a future event from that point in time, so 発車する is natural.

If you used 発車した, it would mean departed, which does not fit the situation.

Here, 十分後 is read じゅっぷんご and means ten minutes later / in ten minutes.

This is different from 十分 read じゅうぶん, which means enough / sufficient.

So context and reading matter:

• 十分後 = じゅっぷんご = ten minutes later
• 十分だ = じゅうぶんだ = it is enough

A learner often gets confused because the kanji are the same, but the meaning and pronunciation are different.

The に marks the time at which the departure happens.

• 十分後に発車する = depart in ten minutes

So:

• 十分後 = ten minutes later
• 十分後に = at/in ten minutes

With time expressions, に is sometimes omitted in Japanese, depending on the expression and style, but here 十分後に is very natural and clear.

は marks the topic, while が more strongly marks the grammatical subject or introduces/focuses on it.

Here, その電車 is already identifiable from the context, so using は feels natural:

• その電車は十分後に発車する = As for that train, it departs in ten minutes

This gives the sentence a smooth, explanatory feel.

If you said その電車が, it would put more focus on that train itself, often with a slightly more contrastive or identifying nuance.

So both can be possible in some contexts, but は is very natural here because the train is already part of the shared context.

その means that.

Japanese has a basic set like this:

• この = this ... (near the speaker)
• その = that ... (near the listener / already mentioned / just referred to)
• あの = that ... over there

In this sentence, その電車 most naturally means that train already being referred to or identified from the timetable/context.

So it is not just any train. It is that specific train.

The subject is omitted because it is understood from context. In English, you usually need to say I, but Japanese often leaves it out when it is obvious.

So the sentence naturally implies something like:

• When I looked at the timetable, I found out ...

This omission is extremely common in Japanese, especially when the speaker is talking about their own action or realization.

Japanese often places a dependent clause before the main clause.

So the structure is:

• 時刻表を見たら = when I looked at the timetable
• その電車は十分後に発車すると分かった = I found out that the train would depart in ten minutes

This is a very common Japanese pattern:

• [when/if/after X], [Y happened]

It may feel a little backward compared with English, but it is normal Japanese sentence order.

In this sentence, found out or realized is probably the best fit.

• 分かる can mean understand
• but it can also mean become aware of / find out / realize

Because the speaker looked at a timetable and learned new information, 分かった here is more like:

• I found out that ...
• I realized that ...

So although 分かった often gets taught as understood, its actual meaning depends a lot on context.